Glycogen synthase kinase-3 (GSK-3) is a serine/threonine protein kinase having α and β isoforms that are each encoded by distinct genes [Coghlan et al., Chemistry & Biology, 7, 793-803 (2000); and Kim and Kimmel, Curr. Opinion Genetics Dev., 10, 508-514 (2000)]. GSK-3 has been implicated in various diseases including diabetes, Alzheimer's disease, CNS disorders such as manic depressive disorder and neurodegenerative diseases, and cardiomyocete hypertrophy [see, e.g., WO 99/65897; WO 00/38675; and Haq et al., J. Cell Biol. (2000) 151, 117]. These diseases may be caused by, or may result in, the abnormal operation of certain cell signaling pathways in which GSK-3 plays a role.
GSK-3 has been found to phosphorylate and modulate the activity of a number of regulatory proteins. These include glycogen synthase, which is the rate-limiting enzyme required for glycogen synthesis, the microtubule-associated protein Tau, the gene transcription factor β-catenin, the translation initiation factor e1F-2B, as well as ATP citrate lyase, axin, heat shock factor-1, c-Jun, c-myc, c-myb, CREB, and CEPB α. These diverse targets implicate GSK-3 in many aspects of cellular metabolism, proliferation, differentiation and development.
Small molecule inhibitors of GSK-3 have recently been reported [WO 99/65897 (Chiron) and WO 00/38675 (SmithKline Beecham)], however, there is a continued need to find more effective therapeutic agents to treat GSK-3 mediated diseases.